The CM diagram of the nearby globular cluster NGC 6397

Abstract

view Abstract Citations (55) References (27) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The CM Diagram of the Nearby Globular Cluster NGC 6397 Alcaino, G. ; Buonanno, R. ; Caloi, V. ; Castellani, V. ; Corsi, C. E. ; Iannicola, G. ; Liller, W. Abstract CCD photometry for faint stars in NGC 6397, combined with a digital reinvestigation of the photographic plates originally used by Alcaino and Liller (1980), has been used to obtain statistically significant samples for the various evolutionary phases, down to V ≡ 21 mag, i.e., more than 5 mag below the turnoff. With a cluster distance modulus of the order of 12.50 mag this implies that main-sequence stars were observed down to MV ≡ 8.5 mag, corresponding to M ≡ 0.5 M_sun;. The authors report evidence for a flattening of the luminosity function for MS stars fainter than MV ≡ 6 mag (M ≡ 0.7 M_sun;), in agreement with previous indications by other authors. It is shown that, to reconcile the cluster age with current estimates for other galactic globular clusters, one needs to assume Z = 10-4 and a cluster reddening of E(B-V) ≡ 0.20 mag, plus an additional reddening of δ(B-V) = 0.04 mag in the location of theoretical isochrones in the CM diagram. Publication: The Astronomical Journal Pub Date: October 1987 DOI: 10.1086/114526 Bibcode: 1987AJ.....94..917A Keywords: Astronomical Photometry; Color-Magnitude Diagram; Galactic Clusters; Stellar Luminosity; Red Giant Stars; Statistical Analysis; Stellar Evolution; Astrophysics; CLUSTERS: GLOBULAR full text sources ADS | data products SIMBAD (112)